Which of These Statements Refers to the Period of Time

Multiple Choice

Which of these statements refers to the period of time following an action potential during which a membrane cannot be restimulated, no matter how strong the stimulus is

A) the relative refractory period
B) the period after the Na⁺ gates have opened and until they are restored to their "closed but capable of opening" conformation
C) prevents the action potential from spreading back over the part of the membrane where the impulse has just passed
D) the depolarization period